[单项选择]

We all have offensive breath at one time or another. In most cases, offensive breath emanates from bacteria in the mouth, although there are other, more surprising causes.
Until a few years ago, the most doctors could do was to counsel patients with bad breath about oral cleanliness. Now they are finding new ways to treat the usually curable condition.
Bad breath can happen whenever the normal flow of saliva (唾液) slows. Our mouths are full of bacteria feeding on protein in bits of food and shed tissue. The bacteria emit evil-smelling gases, the worst of which is hydrogen sulfide (硫化物).
Mouth bacteria thrive in airless conditions. Oxygen-rich saliva keeps their numbers down. When we sleep, for example, the saliva stream slows, and sulfur-producing bacteria gain the upper hand, producing classic" morning breath".
Alcohol, hunger, too much talking, breathing through the mouth during exercise -- anything that dries the mouth produces bad brea
A. thrive on
B. account for
C. originate from
D. descend from

[单项选择]

We all have offensive breath at one time or another. In most cases, offensive breath emanates from bacteria in the mouth, although there are other, more surprising causes.
Until a few years ago, the most doctors could do was to counsel patients with bad breath about oral cleanliness. Now they are finding new ways to treat the usually curable condition.
Bad breath can happen whenever the normal flow of saliva (唾液) slows. Our mouths are full of bacteria feeding on protein in bits of food and shed tissue. The bacteria emit evil-smelling gases, the worst of which is hydrogen sulfide (硫化物).
Mouth bacteria thrive in airless conditions. Oxygen-rich saliva keeps their numbers down. When we sleep, for example, the saliva stream slows, and sulfur-producing bacteria gain the upper hand, producing classic" morning breath".
Alcohol, hunger, too much talking, breathing through the mouth during exercise -- anything that dries the mouth produces bad brea
A. Tooth trouble.
B. Sulfur-rich food.
C. Too much exercise.
D. Mental strain.

[单项选择]We have done all we could and now our cherished project is at the mercy of our new CEO.
A. under the guidance of
B. in the power of
C. on the verge of
D. on the agenda of

[单项选择]If we learn to see what we have to offer one another, then we can ______ our misunderstandings and work towards peace.
A. set out
B. set aside
C. set off
D. set down

[单项选择]One day we all may find it useful to have a(n) ______ for sending documents, writing any pictures across the telephone lines.
A. receiver
B. echo
C. extension
D. facility

[单项选择]Only when we have weighted all the factors involved ______ decide when would be the best time to start.
A. did we
B. we did
C. can we
D. we can

[单项选择]No one would have time to read or listen to an account of everything ______ going on in the world.
A. it is
B. there is
C. as is
D. that is

[单项选择]It rained all the time and so we did not make good time driving to New York.
A. travel at a good speed
B. have a good time
C. content
D. make a good day